M10 (10mm x 40mm) Cup Square Carriage/Coach Bolt & Nut Set - Steel (Pack of 10) Quantity - 10 Bolts & 10 Nuts Bolt Dimensions – 40mm x 10mm Here is what the dimensions mean… M - Metric thread 10 - Diameter of the inside of the bolt, in millimetres 40 - Length, in millimetres (from the base of the bolt head to the end of the thread) Nut Dimensions - 10mm internal Diameter, 17mm external Diameter Material High Quality Steel - Provides protection from external elements and extends the life of the metal used to make these coach bolt sets.